CARACAS—Venezuelan President Nicolás Maduro, the region’s most vocal critic of U.S. policies, hailed Wednesday’s agreement between Washington and Cuba to improve long-estranged relations.

“It’s a moral victory...a historic victory for the Cuban people,” Mr. Maduro said Wednesday in televised comments from Argentina where he was delivering a speech to heads of allied South American states that make up the Mercosur bloc.

“We have to recognize the gesture from President
Barack Obama
; a gesture of courage,” said the Venezuelan leader, who like his mentor and predecessor, the late President Hugo Chávez, accuses the U.S. of trying to topple his regime in a bid to access Venezuela’s vast oil wealth.

On Monday, Mr. Maduro blasted his U.S. counterpart days after the U.S. congress approved sanctions on some Venezuelan leaders allegedly involved in human rights abuses during a crackdown on antigovernment protests that rocked the South American country earlier this year.

Venezuela is Cuba’s strongest ally in the region. Venezuela sends the communist island nearly 100,000 barrels of oil a day in exchange for thousands of Cuban doctors and government advisers.